Highway traffic control system



March 8, 1938. c. D. GEER ET AL,

HIGHWAY TRAFFIC CONTROL SYSTEM Filed Nov. 21, 1929 3 Sheets-Sheet l Qnucntoz D M r a a f? "HALE, do /1,

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March 8, 1938. c. D, GEER El AL HIGHWAY TRAFFIC CONTROL SYSTEM Filed Nov. 21, 1929 5 Sheets-Sheet 2 I gwwnto'o EB Qty/D Gee March 8, 1938. c. D. GEER ET AL HIGHWAY TRAFFIC CONTROL SYSTEM 3 Sheets-Sheet 5 Filed Nov. 21, 1929 2 mm; a M 0 0 M m W HQ u hm M M E Q mm a km (W. W NW Q Q1; Q) s$ NQ$ @Q AH M fi mm M. g Q J W Fm fi Wm .W\ WW mm f BW mm 5* NW. g um WW W m Nmw an H NDQQ WU Qk F a J @n 9% m mm &\ Wm w Na W M Mer- 8, 193

2,110,723 HIGHWAY raarnc common SYSTEM Charles D. Geer and John L. 13inch, New Haven,-

Conn., assignors to The Engineering and Re- Search Corporation, a corporation of Connecticut Application November 21, 1929, Serial No.- 408,863

14 Claims.

Our invention relates to highway traiiic control systems for intersecting streets and more particularly to a system in which a plurality of vehicle actuated right of way controlling devices at the respective intersections are coordinated so that changes of right of way are centrally supervised.

Vehicle actuated traffic control systems have been devised which regulate traflic at the intersection of a highway and a cross street. These systems usually provide that the right of way shall remain on the highway until tramc appears on the cross street; then the right of way shifts to the cross street where it remains for a period variable between a minimum and maxi- ,mum depending upon the number of cars approaching upon the cross street; then the right of way returns to the highway where it remains for a certain time. At the expiration of this time the right of way may again shift to the cross street, it called there by vehicles approaching on the cross street.

Such a system works satisfactorily at isolated intersections, where trafllc conditions at the in- ?5 tersection are not sensibly affected by traffic conditions at'adjacent intersections. When, however, intersect ions are close enough together so that traflic conditions at one intersection affect traiiie conditions'at adjacent intersections, then it is desirable to supervise the operation of all the right of way controlling devices so that traflic may move through the several intersections in a more eflicient manner.

An object of our invention is to provide a 5 supervisory controlsystem for coordinating the operation of several vehicle actuated signal systems at individual highway intersections.

Another object is to provide a supervisory control system of the character designated which shall selectively effect the operation of individual right of way indicating devices.

Another object of our invention is to provide a vehicle actuated traflic control system for use at the intersection of a highway and cross street which is readily adaptable for supervisory control.

These and other objects will be made manifest from the specification and drawings and specifically set forth in the claims.

A traffic control system embodying our invention preferably includes four parts, a signal device at each intersection for indicating right of way, a vehicle operated device located at the side of or in the street, a signaltiming mechanism at each intersection and a supervisory control mechanism connected to all of the signal timing mechanisms.

/The signal device for informing traflic in each street when to go and when to stop may be any of the well known forms, such as red, yellow, and green signal lights; stop, caution, and go signals; semaphores, bells or horns.

The vehicle actuated devices used to send impulses to the signal timing mechanism may be any one of several well known types which are able to recognize the passage of vehicles along the streets and operate an electrical circuit when such passage occurs.

The function of the signal timing mechanism is to receive actuations produced by vehicles operating the vehicle actuated devices and to utilize the impulses created thereby to regulate the operation of the signal device to which it is connected. According to one preferred embodiment of the invention, the system taught in the present application may function as follows: The right of way is constantly on the highway if there is no trafiic on the cross street. As soon as a car approaches on the cross street, and operates the vehicle actuated device located there, the right of way shifts to the cross street, where it remains for a certain minimum time. At the end of this time the right of way returns to the highway, but if other cars should approach on the cross street while the right of way is being given to the cross street, then this minimum time is automatically extendable up to a certain maximum. If this maximum is reached as a result of continuous traflic in the cross street, then the 'right of way returns to the highway, where it will remain for a certain minimum time. At the end of this time the right of way will again shift to the cross street, if cars are waiting on the cross street. If no cars are waiting, the right of way remains on the highway. However, it may be called to the cross street by vehicles approaching on it. The timing elements for carrying out the several timing operations of the signal timing mechanism may comprise oil dash pot relays, mechanical timers, or other means well known to the art.

The'supervisory control apparatus for effecting the desired coordination of the operation of the signals comprises a series of switching devices which are connected to all of the'slgnal timing mechanisms in the group so that circuits may be completed to the several signal timing mechanisms in a predetermined manner. It will thus be noted. that the supervisory control'apparatus may be adjusted to permit traffic in all cross streets to move simultaneously, progressively, alternately, or in any other way as may be necessary to most efficiently handle traiflc passing through the group of intersections. In this way the highway traflic is not interrupted in a haphazard manner but is carefully regulated providing for eflicient new of tramc on the highway and at the same time the cross street is given ample time to use the intersection.

While we have described above a trafllc control system embodying our invention and have shown that this invention includes four interconnected parts, we now describe one complete and specific system embodying. our invention.

In the drawings:

Figure 1 is a view showinga group of street intersections controlled by a supervisory system embodying our invention;

Figure 2 is a detail view of a vehicle actuated device;

Figure 3 is a diagrammatic view showing two vehicle actuated devices connected in parallel;

Figure 4 is a perspective view of one embodiment of the supervisory control mechanism;

Figure 5 is a detail end view of the apparatus shown in Figure 4;

Figure 6 is a view showing the wiring system of the apparatus embodying our invention; and

Figure 7 is a fragmentary view showing a modification of the contact strip shown in Figure 4.

In the following specification, one practical embodiment of the invention is described. It will be appreciated, however, that the specification and drawings are to be construed in a figurative rather than a literal sense and accordingly that many modifications and rearrangements of the parts might be resorted to without departing from the spirit of the invention. For example, while the traffic actuated controls are preferably of the generic type hereinafter described in connection with Fig. 3, and as such to be operated primarily by vehicles, they might be changed to operate automatically or otherwise in response to the passage of any'traffic, as for example by the passage of or deliberate machinations by pedestrians. Likewise, the supervisory control mechanism might be modified or rearranged according to the best practice prevailing at the time of installing a system.

With the foregoing in mind, it will be seen that Figure 1 shows a system applied to the intersections of a main highway and several relatively minor cross streets. The signal means at each intersection is indicated by S. The vehicle actuated means, placed in the streets, are indicated by V. The signal timing mechanisms at each intersection are indicated by T and finally the supervisory control is indicated by SC. These several mechanisms are connected in circuit as indicated by the dotted lines. For this arrangement it will be noted that each signal timing mechanism receives actuations from the vehicles, and controls the signal means, only at the intersection at which it is located. The supervisory control, however, supervises the operation of all the signal timing mechanisms.

The signal means in this particular embodiment consists of red, yellow and green signal lights which indicate respectively stop, caution and go, and one set of these signal lights is visible from each approach of the intersection.

Figure 2 shows one form of vehicle actuated device having a ramp ll sunk in the roadway.

This ramp is pivoted at H so that the wheel of the car passing over it depresses it. A spring l2 returns the ramp to its normal position as soon as the wheel moves of! the ramp. The device is provided with contacts I I which are pressed together whenever the ramp is depressed, thereby closing the circuit between wires I4 and it. Thus we have a closure of this circuit every time a car wheel passes over the ramp.

The vehicle actuated devices in the cross street may be connected in parallel, as shown in Figure 3, and thus, when either device is operated, the circuit between wires M and I5 is closed.

A signal timing mechanism applied to the intersection of the main highway and aminor cross street operates eiilciently with vehicle actuated devices in the cross street alone. As this particular embodiment of our invention shows it applied to a group of such intersections, the individual signal timing mechanisms need receive impulses from the cross streets only, and Figure 6 shows the wiring diagram of such a signal timing mechanism. Furthermore, as it may be occasionally necessary to operate the control system of'one intersection independently, provision is made so that byoperating a switch the individual signal timing mechanism may be disconnected from the supervisory control and operate independently. Flgure 6, when switch 5| is closed against contact 53, shows the wiring diagram of the signal mechanism connected for independent operation.

This embodiment of the signal timing mechanism comprises instantaneous operating relays l6, i8, 20 and 22 and oil dash pot relays ll, It, 2|, 23 and 24. After ten seconds of energizetion oil dash pot relay l1 breaks contact between armature 36 and contact 35. After thirty seconds of energization oil dash pot relay l8 breaks contact between armature 43 and contact 44. After thirty seconds of energization oil dash pot relay 2! makes contact between armature N and contact 55. After three seconds of energization oil dash pot relay 23 breaks contact between armature l2 and contact 13, makes contact between armature I2 and contact 14 and makes contact between armature 8i and contact 82. After three seconds of energization oil dash pot relay 24 breaks contact between armature I1 and contact 16, makes contact-between armature TI and contact 15 and makes contact between armature 68 and contact 61. These oil dash pot relays are constructed so that if at any time the supply of energy is removed, they return immediately to the unoperated position.

When in the position shown, there is no cross street traflic and the right of way has been showing on the highway for at least thirty seconds. As will appear later, all relays are in their nonoperated position except relays 2i and 24, both of which are in their operated positions. This permits current to flow from plus power thru wire 19, the green on the highway and the red lighten the cross street, contact 15, armature 1! and wires II to minus power.

Case I.Sinale. vehicle approaching 0n the cross street; Assume a vehicle to approach on the cross street and operate one of the vehicle actuated devices in said street. This efi'ects a closure between wires l4 and I5 and permits current to flow from plus power thru wire 2!, closed circuit ll-ll, relay II and wire 21 to minus power, operating relay IO. The operating of relay ll causes current to flow from plus power thru wire 28, armature 20, contact 2., wire 32, operating relay II and wire II to minus power. Unless a vehicle happens to stop on one 01' the vehicle actuated devices, closure between wires l4 and I I is only momentary; and consequently relay I9 is operated only momentarily, whichin turn would operate relay l9 only momentarily. However, when relay l9 operateat'it provides itself with a locking circuit thru armature 93, contacts 34 and 95, armature 39 and wire 31 to plus power, and remains in its operated position.

Current nowflows from minus, power thru wire 19, armature 99, contact 39, wire 49, relay 29, wire i9,switch"5|, contact I9, armature 64, contact 55 and wire 59 to plus power, operating relay 2.9. In operating, relay 29 provides a looking circuit for itself thru armature to? contacts 49 and 44, armature '49 and wire 42 to plus power. Relay also provides a path for current from minus power thru wire 19, armature I8, contact 39, wire 49, contact 41, armature, wires 49' and I9, relay 22 and wire 59 to plus power, operating relay 22. When relay 22 operates, armature. 6|

breaks from contact 83,.which de-energizes -relay 24. When relay 24 drops toits unoperated position, armature I'I breaks from contact 15, extinguishing the highway green light and the cross street red light, and makes contact with contact I9, lighting the yellow light thru wire 18,- armature 11, contact 19, yellowlight, contact 19, armature I2, and wire II to plus power. This yellow light is visible from both streets. When relay 24 is de-energized, it also-causes armature 99 to break from contact 61, which de-energ'izes relay 2|. Relayi2l,

becoming de-ener breaks contact between armature 54 and c i tact Ii. The operation of relay 22 caused armature 6| to break from contact 69. It also causes armature 6| to make contact -with contact 62 providing a path for current from plus power thru wire 59, armature 6|, contact 92, relay 23 and wires 64, 96, and 99 to minus power. relay 23 reaches its operated position causing armature 12 to break from contact 19 extinguishing the yellow light. At' the same time armature 12 makes contact with contact 14 allowing current to flow frompluspower thru wire ll, armature I2, contact 14, the cross street een light and highway red light, and wire 89 to minus power. The right of way is now being given to the cross street and the car waiting there may cross. 7

When relay 23 reaches its operated position, it

also causes armature 8| to make with contact 92.

This applies minus power thru wire Ill, armature 39, contact 39, wire 40, contact 41, armature 48, wires 49 and 60, armature 9| contact 82' and wire '83 to relays I"! and I8. Plus power is applied to relay l8 thru wire 4| and relay I8 begins to. operate. Similarly plus power is applied to'relay l'l thru wire '28, armature 29 and contact 3| and relay I'I begins to operate. 'Assuming now that no more cars approach on the cross street, relay y it de-energizes relay 29, breaking contact between armature GI and contact 92, and energizes relay 24 thru wire 58, armature 6|, contact 63, relay 24, wires 65, G6 and 69. When relay 29 becomes deenergized, armature l2 breaks from contact 14,

After three seconds,

extinguishing thegreen cross street light and red highway light. At the same time, armature I2 makes contact with contact 19 completing the yellowli'ght circuit which again lights the yellow light. Ai'terthree seconds relay 24 reaches its by causing armature "11 to break from contact l9, and causes armature 11 to make with contact 19, lighting the green highway light and red cross street light as described above. At the same time, armature 98 makes contact with 91.

providing-a path for currentgfrom minus power thru wire 99, contact 91, armature 99, wire 51,

relay 2| and wire 59 to plus power. After thirty seconds relay 2| causes armature 54 to touch contact 55 and the cross street may again receive right oi. way its car drives up on the cross street. It is to be noted, however, that once the cross :street relinquishes the right or way, it cannot again receive it until after relay 2| has reached its operated pomtiori, because the operating circuitof relay 29, which governs shift .0! right-of way, is made thru the contacts oi. relay 2|. Case II.4 second car approaching on the cross street within ten seconds from the time the cross street first received right of way. The

' relay l1, because armature 29 breaks from contact 9|. Relay ll becomes deenergized and drops back to its unoperated position. This interruption of power isonly momentary as the second car passes the ramp in the cross street and the operating circuit of relay II will again be made at armature 29 and contact 9|. However, it requires a full ten seconds after the circuit is again made before relay l1 reaches its operated position, thus allowing the second car a full ten seconds in order to cross the street. If more cars approach on the cross street, this action as above described will be repeated. When trafllc ceases on the cross street, relay I! will reach its operated position, breaking contact between armature 96 and contact 35, and the operation continues as described in Case I.

C'ase- IIL-Continuous tramc (m the cross street. Whenthis condition occurs, relay I1 is.

continually reset and unless other provision were made, the right of way would remain indefinitely on the cross street. Relay l8 provides this means for limiting'the time the right of way may remain on the cross street.- Relay I9 is energized as soon as the right of way appears on the cross street and is not reset by vehicles as is relay l1. After being energized for thirty seconds, it causes armature to break from contact 44 interrupting the locking circuit of relay 29 which drops to its unoperated position. This de-energizes relays l1, l8, and 22, and the operation then continues as described in Case I. It is to be noted, however, that relay i9 remains energized, and after the right of way has been on the highway for .thirty seconds, relay 2| causes armature 54 to make contact with contact 55, which causes relay 20 to operate. "The operation of relay 29 be readily accomplished by disconnecting the yellow light.

If for any reason it is desired to omit the yellow light from the signal system and have the right of way shift instantly from one street to the other, this may be readily accomplished by replacing oil dash pot relays I8 and N with instantaneous operating relays. I

Referring to Figures 4 and 5 there is shown one embodiment of a supervisory control mechanism for controlling'the operation of the individual signal timing mechanisms at the several intersections. This mechanism consists of a rotatable .drum 84 and associated switch contact members arranged so that the several signal timing mechanisms connected thereto shall be selectively controlled at periodic intervals. Extending longitudinally on the drum is conductor 88. Conductor 88 is connected to slip ring 88. Brush 88 is mounted on conducting arm 8|, and arm 8i is connected to wire" 82. The drum is driven by any uniform speed driving mechanism such as electric motor 88. Brush 88 contacts always with slip ring 88, thus providing that the circuit between wire 82 and conductor 85 is continuously closed. Mounted concentrically with the drum are conducting rings 88, one such ring for each intersection of the group that is to be controlled.

The rings are insulated from each other and are,

mounted in suitable guides 84. Each ring carries a brush 81 which makes wiping contact with the surface of drum 84. Thus once during each revolution of the drum, brush 8! wipes conductor 85. Assuming now that wire 82 is connected to plus power, it will be noted that once during each revolution of the drum ring 86 is charged with plus power. While in this embodiment the contact between the brush 81 and conductor 85 is only momentary, conductor 85 being narrow, Figure '7 shows that the conductor may be widened under a particular brush, thus lengthening the contact between that particular brush and the conductor. Similarly, the contact between the conductor and the other brushes may be made as long as desired. The rings are rotatable in their guides about an axis coinciding with the axis of the drum. Each ring is held in position by set screw 85. By loosening this set screw and by shifting the position of the ring the time of energization of that particular ring can be delayed or advanced as desired. The necessity for this will appear later. Each ring completes a circuit thru wire 88 to contact 52 of a particular signal timing mechanism. Thus when brush 81 wipes conductor 85, contact 52 is charged with plus power.

If now the several signal timing mechanisms are to be operated with supervisory control, each switch Si is moved to make contact with contact 52 instead of with contact 53. It is apparent from the foregoing description that relay 28 governs shift of right of way. Thus when relay 20 operates, rlght of way shifts to the cross street, and when relay 28 is de-energized, the right of way returns to the highway. It will also be noted that when relay 20 is de-energized, its only possible source of plus power is thru wire 50, switch 5|, contact 52 and wire 88. Assuming drum 84 to make one revolution every ninety seconds, then wire 88 will be charged with plus power every ninety seconds.

If a vehicle approaches on the cross street, relay it will be operated momentarily, operating relay i 8, which locks itself into its operated position. This applies minus'power to relay 28 thru wire I8, armature 88, contact 88, and wire ll.

' Plus power, however,- is not applied to relay Ill untilthe brush of the particular ring connected to this particular timing mechanism makes contact with conductor ll. When this occurs, relay 28 operates and causes the right of way to shift to the cross street.

The right of way doesnot shift unless a vehicle is waiting on the cross street because even though the drum does apply plus power to relay 28, the supply of minus power for relay 20 is provided only if relay I8 has operated. Relay I! will not have operated unless a vehicle has operated the vehicle operated device of the cross street.

After the right of way has shifted to the cross street, it will remain there until either relay H or relay l8 operates, which returns the right of way to the highway as described above, under independent operation. It will then remain on the highway until wire 88 is again charged with plus power, this occurring after ninety seconds, when the right of way is again callable to the cross street. Thus the supervisory control establishes the over all length of the cycle. The individual timing mechanisms apportion the time among the intersecting streets.

Assume all the brushes adjusted so that right of way may be given simultaneously to all cross streets. Then when the drum conductor touches the brushes, the right of way shifts to those cross streets only upon which traillc is waiting. Since without supervisory control the highway traillc must be interrupted at some time, the supervisory control provides that this interruption take place ,at several intersections simultaneously, allowing all waiting trafllc to. move at one time. This provides for a minimum amount of delay on the highway.

When connected in this manner, a longer than momentary contact between the drum conductor and the brushes may be desirable, for example, ten seconds. Inthis way a vehicle approaching on a cross street Just after the moment when it was first entitled to receive right of way, need not wait for the next contact, occurring ninety seconds later, but receives right of way immediately.

If the brushes are adjusted progressively around the drum, then the right of way will be yielded by the drum progressively. Thus the last vehicle to get through an intersection, travelling along the highway, would be the last to get through at the next intersection and so on. This clear the highway of traflic. Cross street trafllc commences as soon as this last vehicle has passed. Highway tramc is resumed as soon as the right of way returns to the highway.

As the time and length of time of contact between each brush and the drum conductor is independently adjustable, this provides a wide range of control for the individualintersection within the group. v

Obviously, numerous changes in construction and rearrangements of the parts might be resorted to without departing from the spirit of the invention as defined by the claims.

What is claimed is:

1. In a street trafllc signal system for a main street intersected by a plurality ofcross streets, right of way signal devices at the respective intersections, vehicle actuated mechanisms associated with the respective signal devices for operating the same normally to indicate right of way to one of the streets and stop" to the intersecting street and adapted only when eflective and only in response tovehicle actuation on said intersecting street to reverse the signal indications thereof, and synchronized timing means for the several mechanisms at the respective intersections for rendering said mechanisms eilective sequentially for predetermined time periods, certain oi whichare of extended length, toso reverse the right of way signal indications at each intersection progressively down the main street.

2. In a street trailic signal system for a highway intersected by a plurality of cross streets, right of way signal devices at the respective intersections, vehicle actuated mechanisms associated with the respective signal devices for operating the same normally to indicate right of way to the highway and stop to the cross street and adapted only when effective and only in response to vehicle actuation in the cross street to reverse the signal indications thereof between the intersecting streets, and means for rendering the respective vehicle actuated mechanisms periodically and alternately effective and ineffective to so reverse the signals, both for predetermined times of extended length, in progressive sequence down. the highway.

3. In a highway tramc control system for a group of street intersections, the combination of right of way according andinterrupting signalling devices at each intersection, traflic actuated means in one of the streets at each intersection,

' control mechanisms individual to the several intersections and each adapted when rendered responsive to the trailic actuated means thereat to operate said signal devices in response to actuation of said traffic actuated means to transfer accord of right of way to said one of the intersecting streets from the other, and a supervisory control having a plurality of supervisory circuit means each connected to a different one of said mechanisms to render the latter individually responsive to its associated trafiic actuated means when energized, and cyclically operating time controlled switching means for periodically energizing said several circuit means for individual time periods, some of which are of extended length, in predetermined time relation.

4. In a trailic signal system for a highway intersected by a plurality of cross streets, right of way signalling devices for each intersection, traffic actuated control mechanisms individual to the several intersections for operating individually the respective signal devices normally to maintain right of way on the highway and each adapted when effective to be actuated by traffic in its cross street only to transfer right of way from the highway to the cross street and after a time retransfer right of way to the highway, supervisory control means having separate circuit means to each vehicle actuated mechanism and operable for rendering the latter so effective, and time controlled cyclically operating means for operating the several circuit-means periodically in predetermined time relation and for individual predetermined time periods certain of which extend over a considerable part of each cycle of the cyclic operation, whereby immediate transfer of right of way may be obtained by vehicle actuation occurring at any time in such predetermined time periods only.

5. A traffic signal system for coordinating the control of traffic passing through a plurality of intersections of traffic lanes including in combination, a plurality of right of way signal units located at the respective intersections, tragic ac,

tuated means in certain of said lanes at the respective intersections, control mechanisms in- 1 dividual to the several intersections for operating the respective signal units and each adapted to accord right of way to one lane while interrupting right of way to the cross lane at its associated intersection and adapted when responsive to its associated traflic actuated means to operate said signal unit to transfer right of way to such cross lane from said one lane only in response to actuation of said tramc actuated means in such cross lane, and supervisory control means for the several mechanisms, said supervisory control means including separate circuit means to each control mechanism for rendering the latter responsive to said traflic actuated means when said circuit means is operative and non-responsive when said circuit means is non-operative, time controlled cyclically operating means for rendering the individual circuit means alternately operative and non-operative both for individual predetermined periods of extended length and in predetermined time phase relation, and means associated with said controlmechanism for storing actuation of said traific actuated means on said cross lane occurring during a non-responsive period while right of way is accorded to said one lane to cause said control mechanism during the next responsive period to respond to said actuation.

6. In a trafiic control system for a highway intersected by a plurality of cross streets, right of way signal devices for the respective intersections, vehicle actuated mechanisms individual to the several signal devices each mechanism adapted in the absence of vehicle actuation to maintain said signal device according right of way to the highway and adapted when operative in response to vehicle actuation in the cross street to operate said signal device to transfer right of way from the highway to the cross street, and supervisory control means having separate circuit means to each vehicle actuated mechanism for rendering the same alternatively operative and inoperative, and time controlled cyclically operating switch means for successively energizing and deenergizing said circuit means both for extended periods of time and in predetermined sequential time relation to render actuation of the several mechanisms operative only in a predetermined cyclic sequence along the highway.

7. In a traflic signal system for a highway intersected by a plurality of cross streets, right of way signal devices for the respective intersections, traffic actuated mechanisms associated with the respective signal devices for normally operating the same to indicate right of way to trafiic on one of the streets and stop to the intersecting street and adapted when effective to operate the same to reverse the signal indications between the intersecting streets for a time interval and then return to normal, contact means for the respective intersections for rendering the mechanisms efiective only when operated and ineffective when not operated, synchronized signal timing means for so operating said contact means periodically for determined time periods at least some of which are of extended time lengths, and means for adjusting selectively the several contact means with respect to said timing means for operation of said contact means sequentially, whereby such reversal of right of way signals between the intersecting streets in response to vehicle actuation will occur progressively down the highway and only during such determined time periods.

8. In a street trafllc signal system for a highway intersected by a plurality of cross streets, right of way signalling devices at the respective intersections, vehicle actuated mechanisms associated with the respective signal devicesfor operating the same normally to indicate right of way to one of the streets and stop to the intersecting street-and adapted only when effective and only in response to vehicle actuation in such intersecting street to operate the same to shift the right of way signal indications thereof from said one street to said intersecting street for a time interval and then return to normal, electrical contact means connected with the respective vehicle actuated mechanisms and moveable into open and closed circuit positions to render the individual vehicle actuated mechanisms inoperative and operative respectively to so shift the signal indications, and cyclically operating timing means for operating the several electrical contact means to open and close the same both for extended time periods periodically in predetermined time phase relation.

9. A traflic control system for a series of intersections of cross lanes along a main lane including in combination, right of way signals at the several intersections, traflic actuated means in one ofthe lanes at each of the several intersections, control mechanisms individual to the several intersections each for operating its associated signal when effective to transfer right of way to said one lane thereat from the other in response to actuation of the trafllc actuated means in said one lane, supervisory control means having a plurality of switches, cyclic time controlled means for operating said switches periodically in time relation and for time periods in each cycle, at least some of which periods extend over a considerable part of such cycle, means for determining individually the time periods of operation of the several switches for sequential operation by said time controlled means, and circuit means connecting said switches individually to the several control mechanisms, one switch to each control mechanism, for rendering the respective mechanisms responsive to their respective trailic actuated means when the respective switches are so operated, whereby said mechanisms will be eflective to so transfer right of way only progressively along the highway responsive to traffic actuation.

10. A traffic control system to be installed to govern the flow of traffic along one lane which is intersected by a plurality of successive cross lanes, said system comprising signalling means at the several intersections of said lanes, governing mechanisms for said signalling means to cause the latter normally to accord right of way to said one lane and adapted to be operated to' accord right of way to said lanes alternately and then return to normal, vehicle actuated devices in said cross lanes only, means forming a part of said governing mechanisms and connected to said devices to potentialize the respective governing mechanisms for such operation, when permitted, to cause such alternate accord of right of way by said signalling means in response to actuation of the respective devices, and supervisory control means having a cyclic switching device with a plurality of circuit means operated periodically for determined time periods, at least one of which is of extended length, by said switching device in predetermined time relation to each other, and said circuit means individually connected one to each of said governing mechanisms to periodically only permit such operation thereof when so potentialired, whereby such alternate accord of right of way will occur immediately in response to such potentializing actuation occurring at any time in such extended time period only.

11. In a trams signalling system, the combination of a plurality of corresponding groups of right of way signals arranged to control tratflc at successive street intersections on a main highway, mechanism at one intersection for operating one group of said signals to transfer right of way when conditioned through a cycle back and forth at least once between said highway and the intersecting street, trafllc actuated means in the intersecting street at a.second intersection, a second mechanism at said second intersection for operating another group of said signals at said second intersection normally to indicate right of way to said highway and, when conditioned, operable through a. cycle to transfer right of way from and return right of way to the highway only in response to actuation of said traffic actuated means, and synchronizing means for said mechanisms including switches individual to said mechanisms and operable for so conditioning the latter individually and including time controlled cyclic operating means for operating said switches cyclically in predetermined time relation and including means for determiningindividually the time of operation of said switches by said switch operating means whereby the switch for said second mechanism is operated for a time period lane, and supervisory control means for the sev eral mechanisms and including a plurality of switches, means including a rotating shaft for operating said switches periodically for time periods, at least some of which extend over a considerable time as said shaft rotates, and means for selectively adjusting the position of said switches relative to the rotation of such shaft whereby said switches may be operated sequentially as said shaft rotates, and circuit means connecting each of said switches to different ones of said mechanisms to render said mechanisms effective only when said switches are operated.

13. A traffic control system for a series of intersections of cross lanes along a main lane including in combination, right of way signals at the several intersections, traflic actuated means in one of the lanes of each of the several intersections, control mechanisms individual to the several intersections each for operating its associated signal when effective to transfer right of way to said one lane thereat from the other lane "in response to actuation of the trafllc actuated means in said one lane, and supervisory control means for the several mechanisms and including a shaft, a plurality of switches adapted to be operated by said shaft when the latter is rotated, time controlled means rotating said shaft cyclically to operate said switches periodically for means in said one lane, and supervisory control time periods extending over considerable predetermined parts of its cycle, and means for determining the individual parts of such cycle in which the respective switches are operated whereby said switches may be operated sequentially in such cycle, and circuit means connecting the respective mechanisms for rendering each mechanism so effective only when its associated switch is means for the several mechanisms and including circuit means'connected individually to the several mechanisms each circuit means for rendering its associated mechanism effective when energized, switching mechanism inciuding'a rotat able drum having a contact member fixed on the a surface. thereof, brush members individual to the several circuit' means arranged in wiping contact with the surface of said drum to engage said contact member periodically as said drum rotates, and time controlled means for rotating said drum at uniform speed to energize the several circuit means in predetermined time relation, and means for determining individually an extended length of time during which certain of said circuit means are energized as said drum rotates.

CHARLES D. GEER. JOHN L. BIACH. 

